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At least 1,279 records · Page 71Linked to original sources
PubMed2002

Missing Omo L338y-6 occipital-marginal sinus drainage pattern: ground sectioning, computer tomography scanning, and the original fossil fail to show it.

The Omo L338y-6 occipital region has been recently studied by White and Falk (1999), who claim that it shows a readily identifiable enlarged left occipital-marginal sinus (O/M). These observations are contrary to the direct observations of previous investigators (Rak and Howell, 1978; Kimbel, 1984; Holloway, 1981; Holloway, 1988). White and Falk (1999) further argue that the presence of this enlarged O/M strongly suggests that the Omo L338y-6 hominid was indeed a "robust" Australopithecus. We used direct sectioning and CT scanning to analyze magnified sections of a high-quality first-generation cast of the newly cleaned original fossil. These methods fail to show any evidence of a morphological landmark that can be interpreted as an enlarged O/M, either as an eminence or a sulcus. In contrast, the same techniques used with both SK 1585 and OH5 ("robust" Australopithecus with an enlarged O/M) show extremely visible and palpable enlarged O/M's. Examination of the original Omo fossil confirms that it lacks an O/M. This evidence clearly shows that an enlarged O/M cannot be identified on either the original fossil or a first-generation cast, although this does not rule out the possibility that the Omo L338y-6 hominid was a "robust" Australopithecus. We believe that the differences between observers regarding this feature are most probably due to displacement caused by a crack and the different source materials employed, i.e., the difference between a first-generation cast of the original fossil and a third- or fourth-generation cast of the endocast made two decades ago.

Animals↗
PubMed1997

Intercellular signals and cell-fate choices in the developing inner ear: origins of global and of fine-grained pattern.

The major regions of the inner ear begin to be distinguishable by their patterns of gene expression very early, before the otocyst has closed. Later, individual cells within a neurogenic or sensory patch become committed to specific pathways of differentiation. Insights gained from homologies with invertebrates and from studies of tissues other than the ear, combined with discoveries from screens for mutations affecting development in the zebrafish, are beginning to reveal the genes and signalling mechanisms that control these cell-fate choices in the developing inner ear.

Journal Article↗
PubMed2001

Patterns of evolution in Discula fungi and the origin of dogwood anthracnose in North America, studied using arbitrarily amplified and ribosomal DNA.

The anthracnose epidemic caused by exotic filamentous fungi of the genus Discula threatens the future of the prized flowering (Cornus florida L.) and Pacific (C. nuttalli Aud.) dogwoods in North America. A cross-section of fungi that cause anthracnose in broadleaf temperate trees was characterized using DNA amplification fingerprinting, sequence and secondary structure analysis of the internal transcribed spacers (ITS) of nuclear ribosomal DNA (rDNA), and compatibility of hyphal anastomosis. ITS-inferred phylogenies rejected the null hypothesis of only one fungal lineage, by defining four monophyletic and well differentiated groups, corresponding to Discula sp., D. quercina, D. umbrinella and D. destructiva, with the last two species sharing a common and recent ancestor. In turn, they showed that the dogwood pathogen, D. destructiva, did not evolve directly from an indigenous population related to Discula sp. In this study, rDNA spacers that are generally considered important for protein synthesis but are selectively neutral, appeared functionally constrained and subject to selective sequence diversification. Results confirmed the high variability of D. umbrinella and the remarkable homogeneity and exotic nature of D. destructiva at the genetic level, clarified the taxonomy and phylogeny of Discula, and provided clues as to the origin and diversification of dogwood anthracnose-causing fungi.

Base Sequence↗
PubMed1992

Alterations of protein degradation and 2-D protein pattern in muscle cells of MDX and DMD origin.

Intracellular protein turnover of MDX, DMD and normal muscle was determined by [35S]methionine pulse-chase experiments and subsequent high resolution 2-D gel electrophoresis. In MDX myotubes intracellular degradation of short-lived and long-lived proteins was markedly increased by a factor of 1,4-2,1. In wildtype the rate of degradation of short-lived proteins was approximately 2.6%/h, whereas in MDX these proteins were degraded by 5.7%/h. Long-lived proteins were degraded in wildtype at a rate of 1.8%/h, and in MDX at a rate of 2.5%/h. Furthermore, we have described a 51.000 Da protein with an IEP of 5.1 (p51/5.1), whose net content is highly and specifically reduced in cultured MDX and DMD muscle cells as well as in isolated MDX muscle fibers. Treatment with calcium-channel blockers Dantrolene and Verapamil inhibited the degradation of p51/5.1 in MDX myotubes by more than 90% in contrast to controls.

Actins↗
PubMed1986

Plasmid profiling of epidemic staphylococci from around 1960: a comparison of epidemiological techniques.

Plasmid profiles have been established for 68 isolates of Staphylococcus aureus from 13 episodes of epidemic spread in hospital wards between 1958 and 1962. Despite the original lack of care in preservation of strains the profiles give, in general, the same epidemiological patterns as were established originally on the basis of phage type, antibiotic sensitivity, ward and date of isolation.

Disease Outbreaks↗
PubMed1992

[Cryptogenetic ascites. Attempts at original pathophysiologic explanation of a monomorphic sonographic image pattern].

In 15,645 consecutive ultrasound examinations of the abdomen (1986 to 1988), free fluid in the peritoneal cavity was found in 247 patients by internal trial during 397 sessions (= 2.5%). Most frequent basic diagnosis for the reason of this symptom were tumorous diseases (99 patients corresponding to 40.1%), cirrhosis of the liver (52 patients corresp. to 22.1%) and heart failure (31 patients corresp. to 12.6%, among these complex gayprooft myocardial insufficiency 24, right heart failure 7). Ovarian cysts or cystomas (7), acute/chronic-recurrent pancreatitis (6), Crohn's disease (3), infections (3), rheumatoid disorders (3), nephrotic syndrome (2), and extra-uterine pregnancy (2) were more rarely represented. In 23 patients (corresp. to 9.3%) the cause of an ascites remained obscure. Among these, a high prevalence of the female sex in the premenopausal age was remarkable with a score of 20:3 (statistically significant difference in terms of the other patients of our group). This observation suggests that an ovarian factor plays a role in the development of ascites in the absence of other evident causes. The literature implies that endometriosis is rather prominent, followed by oligosymptomatic infections or inflammatory diseases.

Adolescent↗
PubMed1984

Patterns of polymorphism and linkage disequilibrium suggest independent origins of the human growth hormone gene cluster.

Six restriction fragment length polymorphisms (RFLPs) detected in the human growth hormone-human chorionic somatomammotropin (hGH-hCS) gene cluster were studied in Mediterraneans, Northern Europeans, and American Blacks; the polymorphisms showed that, on the average, one of 500 bases in this cluster is variant. Haplotypes constructed for four of these RFLPs display strong nonrandom associations. However, the strongest associations were between RFLPs that are in homologous DNAs rather than between the physically closest RFLPs. From this and other evidence we argue that duplication of an ancestral hCS gene occurred at least twice, the second event being relatively recent. In other words, duplication of the hCS-L gene to produce the hCS-A gene occurred twice, so that hCS-A genes in humans may have independent origins. Our results imply that chromosomes with absent hCS genes (leading to hCS deficiency) may represent the nonduplicated ancestral unit rather than gene deletions.

Amniotic Fluid↗
PubMed2001

Expression pattern of Drosophila ret suggests a common ancestral origin between the metamorphosis precursors in insect endoderm and the vertebrate enteric neurons.

The RET gene, encoding a receptor tyrosine kinase, is unusual among human protooncogenes in that its mutant alleles are implicated in a developmental defect involving enteric neurons as well as in tumorigenesis. The cells affected in both types of disorders are derived from the neural crest. Targeted disruption of mouse ret has revealed an additional role in kidney development. Here we report the analysis of a ret homolog in Drosophila melanogaster, an arthropod with no neural crest. Drosophila ret (D-ret) encodes a protein of 1,235 amino acids that has all of the domains identified in the vertebrate ret, including a cadherin motif. During embryogenesis, D-ret mRNA is first detected in the yolk sac at the late gastrula stage. In the postgastrula, D-ret is expressed in the foregut neurons, excretory system, peripheral ganglia, and the central nervous system. Thus, despite the wide divergence of early embryonic fate maps between vertebrates and invertebrates, D-ret is expressed in cells that are presumed to be the functional equivalents of the ret-expressing cells in vertebrates. Unexpectedly, D-ret is also expressed in the imaginal islands of the endodermal gut. These cells are proliferation-competent precursors for adult midgut that are diffusely embedded in the growth-arrested juvenile gut. These ret-expressing nonneuronal cells are strikingly analogous to vertebrate enteric neurons in their topography, but not in their cell fate. Our finding suggests a previously unrecognized phylogenetic relationship between the ret-expressing cells in vertebrates and the precursor reserves of metamorphosing insects.

Amino Acid Sequence↗
PubMed2002

Patterns of genetic variation suggest a single, ancient origin for the diploid hybrid species Helianthus paradoxus.

Experimental and comparative evidence implies that homoploid hybrid speciation is a reproducible process, mediated in part by ecological selection. Here, molecular data from the chloroplast genome and 17 nuclear microsatellite loci were employed to determine whether a well-documented homoploid hybrid species, Helianthus paradoxus, has arisen multiple times. Helianthus paradoxus is ecologically divergent from its parental species, and has a disjunct geographic distribution consistent with multiple origins. The molecular data, however, strongly support a single hybrid origin. First, all sampled populations of H. paradoxus are fixed for a single chloroplast DNA (cpDNA) haplotype, whereas local populations of both parental species, H. annuus and H. petiolaris, have multiple cpDNA haplotypes. Second, H. paradoxus populations form a single, well-supported clade (99.8% bootstrap support) in a neighbor-joining tree based on microsatellite allele frequencies. The microsatellite data also tentatively place the origin of H. paradoxus between 75,000 years and 208,000 years before present, indicating that anthropogenic disturbance likely did not play a role in the formation of this species. Finally, the genetic structure of this species is not consistent with passive riparian dispersal, which has been suggested for other wetland plant species, but may be explained by dispersal mechanisms implicated for H. annuus, such as large migratory mammals.

Alleles↗
PubMed1982

Susceptibility pattern of Campylobacter jejuni from human and animal origins to different antimicrobial agents.

The in vitro antimicrobial activities of different antimicrobial agents on Campylobacter jejuni from human and animal origins were compared by using a Dynatech MIC 2000 system. In general, the minimal inhibitory concentration distributions for the human strains were very comparable with those of the animal strains. The animal strains had a bimodal distribution for ampicillin, clindamycin, and tetracycline.

Adolescent↗
PubMed2000

On the origin of the soleus H-reflex modulation pattern during human walking and its task-dependent differences.

Recently, Brooke and colleagues have suggested "that the strong inhibition arising from passive movement about the knee and hip joints, lays down the base for the soleus H-reflex gain modulation seen during human gait." In particular stretch-evoked afferent activity from the quadriceps muscle was emphasized as the most important source of movement-induced inhibition of the H-reflex. To test this hypothesis we examined the kinematics and electromyographic (EMG) activity of the leg during human walking and correlated these with the modulation pattern of the soleus H-reflex. To further test the possible contribution of stretch-evoked quadriceps afferent activity to the soleus H-reflex modulation pattern during walking different walking gaits were studied. In one condition subjects were asked to walk with their knee locked in full extension by a rigid knee brace. In a second condition subjects were asked to walk backwards. During normal walking, the soleus H-reflex modulation pattern is strongly correlated with the EMG events of the soleus and tibialis anterior (TA), but not with hip, knee, or ankle angular displacement or velocity. When subjects walked with the knee locked in full extension, the amplitude of the H-reflex, its modulation pattern, and the task-dependent changes of its amplitude were the same as during normal walking. During backward walking, the H-reflex increases in late swing before activity of the soleus has begun and while the knee is flexing, an observation that highlights central control of the H-reflex amplitude. The effects of imposed flexion of the knee in passive subjects were also reexamined. The knee flexion imposed by the experimenter followed the same trajectory as that which occurred during the swing phase of the subject's step cycle. It was found that imposed knee flexions elicited a burst of TA EMG activity with an average latency of 81.6 ms (SD = 21 ms) in six out of eight subjects. Inhibition of the H-reflex, when it occurred, was associated with the occurrence of this burst. When subjects voluntarily flexed their right knee from an initial quiet standing posture, the inhibition of the soleus H-reflex began before flexion of the knee or that of any other leg segment. Once again the onset of inhibition was closely associated with the onset of activity in the TA. In the discussion section the present observations are examined in light of the predictions made by the movement-induced inhibition hypothesis of Brooke et al. It will be concluded that none of the predictions of this hypothesis were corroborated by present tests done during human walking. In consequence, we suggest that the modulation pattern of the H-reflex observed during normal human walking is centrally determined, as are the task-dependent differences of its amplitude (e.g., standing versus the stance phase of human walking).

Adult↗
PubMedDate not supplied

Utility of the cervical cytologic smear in assessing endocervical involvement by endometrial carcinoma.

OBJECTIVE: To evaluate the possible contribution of cervical cytology in the identification of high-risk endometrial cancer patients. STUDY DESIGN: A retrospective study of 61 patients who had a preoperative cervical cytologic smear and hysterectomy at our institution for endometrial carcinoma. The smear and endocervical curetting (ECC) results were compared with the status of the endocervix in the hysterectomy specimens. RESULTS: Two patterns of malignant endometrial cells were identified in the 25 positive smears: (1) a sloughing pattern, which was the classic rounded cell pattern associated with the exfoliation of endometrial cancer cells, and (2) an abraded pattern in which the cancer cells were present as loosely cohesive, sheetlike groups that retained the original cell shape. This pattern was associated with endocervical involvement by endometrial cancer and overlapped with the criteria for primary cervical adenocarcinoma. Using the histologic status of the endocervix in the hysterectomy specimen as the standard, cervical cytology compared favorably with ECC in predicting the status of the endocervix. Pitfalls included bulky or polypoid lesions that abutted the endocervical canal and smears taken when the endometrium was sloughing. Reactive endocervical cells presented diagnostic dilemmas in patients who had had endometrial sampling prior to the smear. When restricted to cases in which the smear preceded endometrial sampling, the smear was superior to ECC in predicting endocervical involvement. CONCLUSION: These results suggest that preoperative smears may be valuable in assessing cervical involvement by endometrial carcinoma. It is recommended that a smear be performed as an initial procedure in any woman with complaints of abnormal uterine bleeding.

Cervix Uteri↗
PubMed1988

The electroencephalographic pattern during electroconvulsive therapy: V. Observations on the origins of phase III delta energy and the mechanism of action of ECT.

The generation of the spike-wave activity of Phase III of ECT seizures is attributed to the recurrence of synchronized, prolonged periods of intense inhibitory current flow (hyperpolarization), and associated rebound spike bursts, produced by the inhibitory circuit relationships and intrinsic electrophysiological properties of thalamic neurons. An anatomical and neurophysiological model of the development of generalized, synchronous 3-Hz spike-wave seizure activity is proposed which outlines the origin, maintenance, slowing, and termination of this fundamental seizure rhythm. Phase III inhibitory current flow (delta energy) and/or spike bursts may bring about therapeutic benefit by initiating a chain of agonist-independent and agonist-dependent events which results in long-term augmentation of serotonergic and noradrenergic neurotransmission and diminution of cholinergic neurotransmission in the forebrain. A specific anatomical and functional model of the mechanism of action of ECT is proposed, in which: (1) adrenergic and cholinergic pathways in the forebrain are assumed to be massively stimulated during ECT seizures, whereas serotonergic pathways are assumed to be inhibited during these seizures; (2) the beneficial effects of ECT are considered to be more dependent upon ECT-induced changes in 5-HT neurotransmission than upon alteration of noradrenergic function; (3) these beneficial effects involve up-regulation of 5-HT2 and down-regulation of M1- and M2-muscarinic receptor densities by both agonist-independent and agonist-dependent mechanisms, coupled with functional augmentation of noradrenergic neurotransmission; and (4) these effects may be brought about by Phase III inhibitory current flow- and/or spike burst-induced alteration of the function of second-messenger generator systems.

Delta Rhythm↗